33 



left side as the visceral mass is reached. Just before the 

 region of the pericardium and digestive gland is entered, 

 a peculiar caecum is to be found on the oesophagus 

 (fig. 12, Ln. g.). Its walls are rather more thick than 

 the part described above, and resemble the short piece 

 now left between caecum and stomach. The caecum can 

 be easily seen in simple dissections, for the oesophagus 

 has now left the head region and is visible without any 

 incision whatever at the surface of the visceral mass on 

 the left ventral edge. The caecum itself lies just behind 

 the pericardium (fig. 12, Caec). 



The Stomach — that part of the alimentary canal 

 into which the ducts of the large digestive glands (the 

 so-called liver) open — is a bag of considerable size, with 

 one surface lying against the digestive gland and the 

 other surface against the bounding integument. Thus 

 the stomach is clearly visible without any dissection. 

 Curiously enough, it is attached strongly by short muscle 

 strands to the epithelial layer of the body wall, so that 

 the latter, which can be easily removed from the other 

 parts of the viscera, is only pulled away with difficulty 

 from this area. 



The stomach (fig. 12, St.) is very irregular in shape. 

 It is flattened, so that there are two more important 

 surfaces, and it is elongated in an antero-posterior 

 direction. The oesophagus opens into it ventrally about 

 midway between the point of origin of the rectum and 

 the posterior apex of the stomach. Just before entering 

 the stomach the oesophagus passes under a somewhat 

 conspicuous lobe of this organ, which is marked with 

 radiating striae and lies between oesophagus and intestine 

 (fig. 13, Dg.")- 



The markings on the external surface of the stomach 

 correspond to ridges which occur on the inner surface and 



